The present invention is generally directed to the processing of food, and more particularly to a machine for cleaning shrimp.
The edible portion of a shrimp is covered with a shell and contains an inedible sand vein near its back. This vein must be removed before a shrimp is canned, frozen, or cooked and it is also desirable to remove the shrimp meat from the shell.
Hand removal of veins and hand shelling is tedious and inefficient and consequently is most undesirable when large numbers of shrimp must be handled. Many shrimp are seined from water in hot climates and the shrimp must be promptly processed in very large numbers. In order to reduce the required amount of hand work for removing the veins from shrimp and separating the meat and shells, various forms of shrimp cleaning machines have been devised. Machines of this type are fully described and claimed, for example, in U.S. Pat. Nos. 2,850,761; 3,159,871; 3,214,789; 3,238,561; and 3,751,766. The machines disclosed in those patents generally include a carrier comprising a plurality of circularly arranged clamps which grip the shrimp and transfer the shrimp along a circular path through various processing stations which clean the shrimp and separate the shrimp meat from the shrimp shells. During the cleaning of the shrimp, the machine cuts the shrimp lengthwise along the shrimp sand veins, and, rakes debris from the sand vein area of the shrimp to assure thorough removal of all material previously in the sand vein.
Each of the circularly arranged clamps includes a pair of clamp jaws which are mounted for relative pivotal movement. Springs acting between the clamps close the jaws and suitably positioned cams open them. As the clamps revolve in a circular direction to transfer the shrimp through the various processing stations of the machine, the clamps are held open by a ring cam disposed within the inner periphery of the clamps, and subsequently are spring-closed for gripping the shrimp shells.
The clamps are closed by springs coiled inside the clamp as shown, for example, in U.S. Pat. Nos. 2,850,761 and 3,214,789. The ring cams then allow the clamps to open and close at the desired location as shown in the patents. Ideally the clamps should close sufficiently to make the meat and shell tight such that when the cutter splits the shell open, the meat is released and allowed to spread open to expose the vein cavity.
The springs have to be very strong because some shrimp are very firm and have bulky portions or are of a semi rigid structure. But if soft meat and/or brittle shell is run through the shrimp processing machine then the shell will crack along the edge of the clamp and release the load on the meat due to the force exerted on the shell such that there is no blossom affect after a cutting operation and the vein is not properly exposed.
This invention allows a very light spring to initially close the clamps sufficiently during the cutting operation subsequently the spring biased cam of the present invention serves to close the clamps the rest of the way to permit blossoming of the meat and exposure of the shrimp vein. The cam must be positioned between the cutting and deveining station.
In order for the deveining of the shrimp to be successful, it is necessary for the sand vein of the shrimp to be exposed to the deveining process stations. Because there are a variety of different species of shrimp, each having shells of various thicknesses, the prior art machines have not always been able to expose the sand vein to the deveining stations through the cutting of the shrimp shells lengthwise along the sand vein and by the normal gripping of the shrimp shells by the clamps for transferring the shrimp. One species of shrimp in particular, known as Australian shrimp, have tough membranes and a brittle shell and thus, are particularly difficult to open for exposing the sand vein. Machines of the prior art have not always been capable of fully exposing the sand vein of this variety of shrimp and others to facilitate deveining of the shrimp.
It is therefore a general object of the present invention to provide a new and improved shrimp processing machine.
It is a further object of the present invention to provide a shrimp processing machine includes an improved cam arrangement which acts upon shrimp carrier clamps to cause the clamps to apply forces on the shrimp shells to permit the desired of splitting the shrimp shell and the exposing of the sand vein of the shrimp for subsequent removal.
It is a still further object of the present invention to provide such a shrimp processing machine in which an improved cam arrangement is arranged to cause the carrier clamps to exert an increased maximum predetermined force or pressure on the shrimp after the splitting of the shrimp shells along the sand vein in the cutter station. The cam arrangement is further arranged for positively returning the clamps to an initial operative position.
The invention therefore provides a machine for processing shrimp comprising carrier means including spring actuated clamp means for gripping the shrimp and transferring the shrimp through the machine, first cam means for causing the clamp means to open to receive the shrimp, and second cam means for causing the clamp means to exert an additional force on the shrimp for splitting the shells of the shrimp open. The second cam means includes a pair of spaced apart cam members arranged for pivotal movement relative to each other from an initial operative position, and biasing means for biasing the cam members apart to assure contact with the cam followers and return the cam members to their initial operative position.